A Heart Grows (With More People To Love)
by KeepSaying
Summary: When there's a newborn Stark on the horizon Peter starts to question his place in the family he has come to view as his own. Good thing Tony has an abundance of parenting books at his disposal and knows exactly (kind of) what to do.


**A/N**: Next one of the 1k prompts for our blog weartirondad on tumblr. Check it out! My plan is to finish these in April. But we'll see. Hope you enjoy!

**"You'll always be my kid."** \- _Tony and Pepper are having a baby and first Peter is excited but then he hears how parents and adults in general will hover around the new kid and tend to forget older siblings. Naturally, he thinks Tony will forget him and he tries to alienate himself from his mentor so the rejection won't hurt so much. But it just leaves both of them miserable. **(irondadgroupie on tumblr)**_

* * *

Peter wasn't an ungrateful kid. At least he didn't think he was.

Sure, sometimes he'd get annoyed because his aunt would tell him to do the dishes again and not to stay up too late video chatting Ned but that just fell under normal things teenager did, right?

Compared to Ned's sister who was several years younger than them and was already scraping dangerously at the feared puberty door, he was a really nice, easy-going kid.

After having lost so much he appreciated what he still had.

He loved his aunt unconditionally and he told her every day, went to school happily most days, always eager to learn even when Flash tried to bring him down. He held on closely to Ned as his best friend and guy in the chair, studied for school and Decathlon and went out as a low-level superhero in his spare time, saving people or simply putting smiles on their faces.

On top of something he considered already a pretty blessed life despite everything that might've made it seem to be anything but, he had also gotten to meet his childhood hero. Not only that but he got to hang out regularly with said childhood hero, spent time with him in his ridiculously big and shiny lab to tinker, had movie nights and inside jokes and he had his own room in his monument of a tower.

Somewhere over the course of the past year he had made place in his life for the hero-turned-mentor-turned-surrogate-dad and everything that came with their new growing relationship. They had a schedule when they were supposed to train, when it was the billionaire's turn to pick the boy up from school and they even planned their trips to get ice cream so they would eventually have tried out every single one in New York City. (It just might take them a while but they would make it.)

He didn't care about the money, either, and didn't even take it most of the time, happy with where his aunt had gotten them and their way of living even after – well – after everything they had been through together.

He probably had it worse than some but he certainly had it better than others.

Point was, Peter appreciated every little thing he got, every single person in his life, and he loved getting to spend time with The Tony Stark but he wasn't an idiot either. As a matter of fact he had it certified that he had a genius level intellect.

He knew the man was busy more often than not and that made it mean that much more when he consciously made time for Peter in his tight schedule. There was a warm feeling of belonging, of family and being loved whenever he heard the man lazily cancel meetings _("Mister Stark you can't stand up the president to watch Solo with me!")_ just to spend time with him – a no-name kid from Queens.

One day, when they had been at the tower and someone had called the billionaire away to put fires out at Stark Industries, Rhodey had told him a little bit about how his mentor had been before they had met, how much Peter reminded him of his best friend when he was a teenager and just how hell- bent he was on not turning out like the father he never talked about.

Peter was perceptive enough to realize that the man he had looked up to ever since he could remember was in turn thriving on taking care of him, on having someone to teach and coddle and _parent_.

So when the newly wedded pair told him about them expecting a baby, eyes alight with wonder and excitement and a little fear, he was beyond thrilled for them.

All his life he had always wanted to have a younger sibling, a tiny someone to carry around and cuddle and love, and he had never really been able to actually realistically dream about it. May and Ben had never wanted kids to begin with but they took him in and loved him like they would've their own, like he was their flesh and blood and he was so incredibly thankful for the family, for the home, they gave him.

Now he could dream about more, however. He could dream about getting to be a sort-of-brother to his sort-of-dad's baby and he already had a few pages worth of list full of things they would do together.

What he realized later on and which might've been the reason why Ned's smile had faltered the tiniest bit when he had announced the good news to him – because Ned actually had a smaller sister and he _knew_ – was that once a younger sibling got there, more often than not the older one got to spend significantly less time with their parent.

Which made sense, of course.

The baby needed a lot more attention and help because they actually couldn't feed and dress themselves and weren't able to change their own diaper. They were completely helpless whereas Peter himself was old enough to stay home alone for the weekend (although he rarely did because either May or Tony were always there), cook for himself, do his laundry and safe people as Spider-Man.

It was ridiculous, really, because Mister Stark wasn't his dad and he wouldn't be jealous of a newborn, he _refused_. Especially not when the mere thought of his own child made his mentor's eyes light up with so much love and adoration whenever he talked about them.

Still, he couldn't help but feel his eyes burn with tears and his heart plummet to his stomach with a sense of betrayal when he woke up and checked his phone only to find a message from the man he looked up to so much, asking to take a rain check on their lab date because of the prenatal classes he was attending with Pepper.

He rubbed the sleep sand from his eyes, stomach coiling with loss and tossed the phone to the side after having typed a short reply.

_Stupid_, he cursed himself, _you're being silly and childish and stupid._

The fact of the matter was, though, that in the end the _#1 Iron-Dad_ mug he got him for father's day and their matching shirts and their scheduled times together wouldn't mean a thing. Not when the baby got here.

Tony wasn't really his dad and he would have a child of his own – his actual, biological child. The kid would be loved beyond measure by everyone around them. They would have their mum and dad, several aunts and uncles and Peter himself wrapped around their little finger in no time.

There was a tiny, silly, _childish_ part in his chest that clenched painfully and stupid, _stupid_ voices screaming over each other in his head telling him that his days at the Stark residence were numbered and would be over not before too long.

It didn't matter, though, Peter had been fine before Tony had come along and he'd be fine with spending less time with the man, as well. He had been perfectly fine doing his calculus homework on his own and creating his web-formula and –

"What's gotten your panties in a twist on this beautiful Monday morning?"

He glared at his aunt who simply raised an unimpressed eyebrow at him, watching him intently as he silently shuffled into the kitchen and plopped down on his chair, trying his best not to look too miserable. Considering the look she shot him he guessed he was failing spectacularly.

"Nothing," he grumbled, reaching for the cornflakes and dumping them into his bowl with a little more force than necessary. They spilled over, making a mess on the whole table and suddenly he was overcome with a barely controllable urge to scream.

"Peter, sweetie –"

"I'm fine," he gave back curtly and swatted her hands away that were instantly at his side to help clean up. He didn't want her help. He didn't _need_ it. He just wanted to get out and go to school and get this horrible, awful, terrible day over with.

Of course she ignored him and brushed his mess over to the side so he could put down his bowl again, wordlessly handing him the milk to pour over what he had managed to actually get to its destination.

He started eating rather listlessly just going through the motions of picking up the spoon, filling it with the sweet substance that tasted like ash on his tongue when he swallowed it and when he was done and May had finished her morning tea and he was about to flee the scene, she reached out to pull him into a hug.

This was normal. She did this every day. Only today it felt more deliberate, her grip a little tighter, a little warmer and he almost relaxed into her touch. Almost.

"Tony called me last night," she said, pausing when he – against his better judgment –went perfectly still in her arms and started to push away. "He told me about the prenat class and to make sure you get your weekly dose of fast-food. So I was thinking we could order in and watch Dancing On Ice instead? We haven't had Thai in ages, what do you say?"

He nodded mechanically, head spinning because his aunt sounded like everything was completely fine. As if this wasn't the beginning of the end of his relationship with Tony Stark. And he hated himself for wanting to whine about it, how he wanted to complain about a billionaire, superhero and soon-to-be father not having enough time to baby him.

He wanted her to comfort him and to tell him that his mentor would still have time for him and that he wasn't less important to the man just because there would be a new kid on the block soon. At the same time, though, he wanted to hear that she had never liked Tony to begin with and that he was better off without him.

"Hey baby," she frowned, voice soft as she pressed a kiss to his temple, "What's wrong? Are you sad he stood you up? I can tell him that he's a shit head if you want but you know he only has four of those classes, right?" Her hand carded through his hair reassuringly, making tears spring to his eyes that he refused to cry.

_Yeah, but he'd have a lifelong of the baby_, he didn't say because it would've sounded stupid and jealous and downright mean.

"No, of course not," he said instead and gently extracted himself from her arms, shooting her a smile he hoped looked not as desolate as it felt. "It's just one time."

* * *

Only it wasn't just that one time because when Thursday rolled around and Happy was scheduled to pick him up from school, he texted the driver that he had too much homework and an essay to finish so he couldn't make it to their weekly movie night.

He told himself Spider-Man was needed in Queens on Saturday when they were supposed to have brunch and he had promised Ned to show him some cool moves and his newest web formula after so he couldn't just go over in the afternoon either.

Over the next couple of weeks he realized just how packed his schedule was.

Suddenly he had too much to study for with Decathlon coming up in only a few weeks' time and helping May around the house and geeking out over the newest Lego catalogue with Ned and trying to keep his neighborhood safe at night.

There was nothing to it, really.

It wasn't like he was avoiding Tony Stark. That would be ridiculous.

He was just too busy with his own life to be able to make it to the tower for their regular meet-ups. There'd come a time when he wasn't so occupied anymore and it'd go back to normal. Only then, he thought, the baby would already be there and the older man probably wouldn't have time for h –

"Peter! Peter!" Ned's excited voice pulled him from his mulling thoughts and he blinked twice, a little irritated at how cheerful his best friend was. Why couldn't he be going through a crisis, too? "Look, it's Iron-Man!"

That got his attention.

His head snapped up in disbelief, mouth already forming a not-so-nice comeback for Ned for lying to get his attention and neck cracking loudly at the fast movement, but Ned had not been lying. (Really, Peter was an asshole for thinking he would in the first place. Ned was his best friend and he was just in a sour mood.)

Tony Stark was, in fact, leaning against the body of one of his flashier cars, casually swiping away on his phone, pointedly ignoring all the wide-mouthed stares and the small crowd of students who just sort of stopped as soon as they stepped into his vicinity.

Some sixth sense seemed to alert him to Peter's presence, though, because the second the boy took the last step off the stairs he looked up with a wide smile and waved. Or maybe it was F.R.I.D.A.Y. telling him he got out but he liked the thought of Tony being so in tune with him that he actually sensed him without some fancy tech. How could he, though, when they hadn't seen each other in three we –

"You know, I can actually hear the wheels in your head turning. You're thinking that loudly, kid."

The teenager blinked at the man standing right in front of him who had expertly made his way through the crowd of awed kids without Peter noticing only to ruffle his hair and greet him and Ned who was gleefully excited at being recognized but didn't let out much more than a "Hey Mister Stark" much to Peter's relief.

He still hadn't said a word or even acknowledged his mentor's presence he realized when the gentle hand on his shoulder tightened momentarily and concern flitted through the warm brown eyes that were holding his gaze.

"Has he been like this all day?" Tony asked, question obviously directed at Ned who frowned and shook his head.

"He's been a bit off for a few weeks but like," he shrugged and pulled on the strings of his backpack – something Peter knew he always did when he was nervous, "Not dangerously close-to-the-cliff off. Just, _off_, you know?"

Peter saw the tiny moment of hurt cross Tony's features before he stilled them into sobriety again. He knew why, too, because Tony hated when he was like that – almost apathetic – and he usually found a way to cheer him up or at the very least made him not feel so alone anymore but he had been avoiding him and so he never even had the chance.

Tony Stark was someone who fixed things and he hated being kept out of the loop so he couldn't even try. Peter knew he hated feeling helpless more than anything.

Maybe now was a good time to start speaking up. He could hear his mentor's heart rate pick up and the way his eyes flitted back and forth between the kid, the crowd and his fancy watch looked a lot like he was preparing to take off flying with Peter any second and he'd really rather not do that right now.

"Sorry," he murmured instead of a greeting, "I've just been pretty tired, is all." Tony didn't seem too convinced by his lie but he kept it up anyway, "Uh, what are you doing here? Where we supposed to be meeting today?"

He was pretty sure that they weren't supposed to meet up before the weekend which is why he had already prepared a new excuse to give all concerned adults in his life.

Okay, so maybe he had been avoiding the man a little bit.

"Nope," Tony shrugged and put his arm around his shoulder, dragging him along to the car. "But I checked your schedule and checked with May and she said you'd be free and that you weren't going to go out tonight anyway, so I thought we could have a sleep over. The bots have been missing you and Pepper's worried you're abandoning her because she's now double your size."

Really, if he didn't know any better he would've said that his mentor sounded pretty nonchalant about the whole thing but Peter did know better. He knew him good enough to hear the edge to his overly cheerful voice he only kept up because there were other people around. There was worry in there, confusion and a little hurt. The emotions were blending together, hidden so perfectly behind a smile that he was sure didn't quite reach the eyes covered by the trademark sunglasses sitting on the bridge of his nose.

"That," he started and leaned into his mentor's side experimentally, raveling at how perfectly he still seemed to fit there. He cleared his throat, "I'd like that. I miss them, too." Which was stupid because he was the one who had cancelled all their meetings. So really, if anyone was at fault here it was him.

Tony nodded, seemingly appeased for now and thumb absentmindedly rubbing over the fabric of Peter's t-shirt where his hand was still resting as he turned to Ned. "Do you need to be chauffeured anywhere?" he asked him but before he could even finish the sentence, his friend was already shaking his head and Peter couldn't help but feel grateful for it.

Now that his mentor was here, he really wanted nothing more than to spend some time alone with him and he was already dreading having to talk about why exactly that had taken him so long.

* * *

"So," he asked after they had gotten into the car and Tony had started driving more or less in silence, only tapping his fingers on the wheel to the rhythm of Black Sabbath's Iron Man. "Are we going to be working in the lab? Do you need my help with some updates?"

Why did he feel so awkward? They had passed this stages ages ago. He hadn't floundered while talking to Tony for almost a year now and now he was back to overthinking every little word and every single emphasis. What was _wrong_ with him?

"Do you have homework?" the question came in return, completely sidestepping Peter's own awkward rambling. If it had been a month ago he would've called the older man out for answering a question with another but it wasn't so he didn't.

It put an emergency brake on his racing thoughts, though, bringing them to a standstill and making the voices in his head go quiet for once. He nodded haltingly. "A few pages for calc and I have to finish writing a short story in Spanish."

Tony hummed at that but didn't immediately reply. His hands were gripping the steering wheel so tightly his knuckles were turning white. Peter watched him intently as he forced himself to relax. It was a visible struggle but one he obviously won and a bit of the tension that he hadn't even realized the other man had harbored seeped out of his shoulders with his next sigh.

Guilt started gnawing at him. Was Peter stressing him out that much? Maybe he really should've stayed away –

"Then you're gonna do your homework first and then we'll catch a movie," he decided then paused and when he started talking again he sounded hesitant, only a shadow of his usual self-confident snark. It felt wrong for Tony Stark to be nervous talking to one Peter Parker, like they had been freaky-fridayed only that Peter hadn't gained any of imperturbability he associated with his mentor.

"Do you, uh, I mean, you can always ask me for help with the tasks, you know that, right? My Spanish grammar might be a bit rusty but I think – well," he sighed, "Just, I want you to know that I'd be happy to help if you need it."

The tiny gnawing had turned into a solid mass, one that was currently forming a big lump in Peter's throat and he grimaced a little, swallowing past it. "Thank you," he said, voice so quiet it wasn't much more than a whisper, "That'd be great."

The soft smile the billionaire shot him was almost enough to make the shame ease away. Almost. Because he was acutely aware that despite everything, he was the one who had made it weird again, who had put up the walls between them once more that they had spent so long meticulously disassembling the first time around.

And why? Because he was jealous of a fetus.

Peter exhaled deliberately, relaxing the hand that had been clenched at his side as he turned to his mentor as much as the seatbelt would allow. He used to do that all the time – left ankle tugged underneath his right thigh, right side facing the front window, arms gesturing widely and eyes sparkling with excitement, trying to catch his mentor's gaze whenever he looked up from the street.

Now he was angled a little awkwardly in his seat but with the shift he already felt more comfortable – more at home – than he did before. And he tried, maybe a little too hard, to sound like his normal exuberant self.

"We're supposed to be writing about a misunderstanding," he told him, cringing when his voice came out squeaky but Tony didn't seem to care, he simply nodded, small smile indicating that he was listening and so Peter continued describing his general plot idea, letting his mentor weigh in with his own ideas every once in a while.

When they parked the car about fifteen minutes later, Peter was considerably more at ease and the tiniest version of a grin was resting comfortably on his lips as he shook his head at yet another ridiculous notion. Just like that, they were back to normal and it felt like coming home.

Peter jumped out of the car as soon as it had stopped, waiting until Tony got out so the man could sling an arm casually around his shoulders and lead him to his workshop for his afternoon snack and to start working.

His favorite flavored Doritos (nacho cheese) were filling the top drawer and from the door of the mini-fridge filled with yellow peppers, cucumber, tomatoes and bananas ("Growing mutant teens need vitamins, okay?") his own picture was grinning back at him.

It was a random, dorky snap of him hanging from the ceiling in his Hello Kitty PJs and his favorite Iron Man t-shirt, tucked into the waistband so it wouldn't fall into his face. His hair that was way too long for his liking was hanging down in messy curls and he was aiming the web shooter on his free hand at the man behind the camera, Tony.

On the couch was his favorite blanket and a few books he liked to read in his downtime were strewn across the counter. His work utensils hadn't been touched since he had last moved them, just waiting for him to get back to work and Dum-E beeped happily when he made him a green smoothie like he always did.

It was obvious that the place had been waiting for him to get back and he realized, with a heavy heart, that sometime during the past year the lab that used to only have one owner had morphed so Peter fitted right in. Tony and the bots and everything had moved to make room for him. And he had pushed them away out of fear of being left out.

* * *

Being in the workshop now, scribbling away in his notebook while Tony worked on some new tech for Stark Industries felt liberatingly familiar. The bots' quiet whirring whenever they moved and their creator's small chuckles or annoyed groans a similarly calming background noise as May shuffling along in the kitchen was back in Queens.

He hadn't realized just how much he had missed this.

"¿Terminaste?"

"Claro que sí." Peter looked up with a cocky grin, finishing the last sentence on his assignment with a flourish before throwing his pen on the desk and watching it roll a good bit until it came to rest just short of dropping off the table completely. He pushed away his notes with an exaggeratedly relieved sigh, "Por fin."

The billionaire returned his smile fondly and, instead of continuing his own typing like Peter thought he would, he rolled his swivel chair closer, hands unusually fidgety in his lap.

"I've got something for you," he said, the casualness from before suddenly gone as he switched back to English.

"Oka-ay," he dragged the word a little, tasting the question on his tongue experimentally as he tried to figure out where this was going but came up empty. (If he chose to ignore the self-destructive voices in his head telling him he was going to get dumped, which he decided to do.)

"What is it?" he wanted to know, cocking his head to the side quizzically.

That seemed to be all the incentive his mentor needed because his posture changed from uncertain to man-on-a-mission in the blink of an eye as he turned around and started shuffling back towards his desk only to pull out a small parcel from one of the drawers. Without so much as a heads up he threw it over to a baffled looking Spiderling that caught it without a problem.

"Open it."

While the voice might have sounded a bit gruff to anyone else, Peter thought there was an edge of gentleness there, too, and when he started opening the package ever so delicately he could feel his mentor's eyes on him, watching him like a hawk.

It was a… t-shirt? Yeah. A plain white t-shirt with some sort of print –

His eyes grew wide when the meaning of the words finally registered in his brain. "So, it's a… she's going to be a girl?"

There, blindingly bright and impossible warm, was the excitement over the newest addition to the Stark family that had been shoved aside for some unfounded jealousy weeks ago and it was – it was exhilarating. Every part of his being seemed to be buzzing with a sheer endless amount of love. Right now there was no place for envy, the green-eyed monster in his chest didn't get any more nutrition.

The big bold letters on the front of his new t-shirt, his most important outfit to-date including his multi-million-dollar-high-tech-vigilante suit, were announcing him as a part of the family he had silently feared he'd be kicked out of to the whole world.

_TREAD CAREFULLY, I'M HER BROTHER_

Her brother, her brother, her brother – his world kept spinning around the two words like they were the axis everything would pivot around from now on. The center stone of his life moving forward. And it some ways it felt true.

His mentor didn't seem to realize the amount of emotion and relief he had triggered in the boy and he kept talking, although his voice sounded far away in Peter's ears.

"Yeah, we had the ultrasound the other day and they're pretty sure. We even got a few pictures if you… if you want to see them."

That brought him back to reality, the lightheaded spinning coming to an abrupt and painful stop as he detected the hurt in the older man's voice.

He looked down, hands that were still gripping the t-shirt tightly sinking down into his lap as he felt the guilt wash over him once more. "I'm sorry… for having been so absent lately. I just –"

"No, none of that." Tony had crossed the distance between them and his hands came to rest on Peter's impossibly gently, his thumb hovering over the teenager's knuckles as if waiting for consent which he gave in form of a barely visible nod.

When Peter looked up, he was surprised to find his vision swimming with tears threatening to fall. It was like all the feelings he had been harboring for weeks, that he had kept close to his chest and that had slowly started to poison his heart were unraveling and he was coming apart at the seams.

But Tony was there.

He was right here, tightening the grip on his hand and pulling him forward ever so slightly until Peter's face was buried in the crook of his neck and the tears that were now running freely were soaking his shirt.

And through it all, Tony was there, humming gently because he knew the tiny vibrations were the easiest way to calm the shaking kid in his arms down.

"You don't have anything to be sorry for, Pete," he continued when the sobs had quietened down to occasional sniffles but his hand that had come to rest on the top of his mentee's head never stopped the carding motion.

"I – I mean, me being me I was freaking out considerably when you started cancelling all our meetings but then I, uh," he chuckled, the feeling of his chest moving resonating in Peter's own body, "I actually started reading some of the books the woman doing the prenatal class recommended and there are actually a few chapters in them about … well, about older siblings tending to feel left out – "

"But I'm not –"

"But you are, Pete," he interrupted him gently, pushing the boy upright until he could meet his puffy eyes, "Or at least you are if you want to be."

He let Peter have the choice, watching him patiently without trying to push in one direction or the other. If he was being honest, though, it wasn't a question, it wasn't a choice he had to consciously make because in his heart he knew what he wanted and so he nodded, timidly.

"I do," he whispered, voice barely audible and sounding oh-so-young.

The answering smile was radiant and the hand that had moved down to rest on his shoulder tightened its grip momentarily.

"That's," Tony grinned – an outright, full-teethed grin that split his face in half – "That's great."

It almost felt like this was it because normally the genius didn't linger in the area of raw emotions any longer than necessary but apparently the parenting books were already making their mark on the usually emotionally constipated engineer because he kept going, voice turning serious once more and impossibly loving.

"No matter what happens with our principessa, though, I want you to know, that her joining this family doesn't make you any less a part of it. Pepper and I could have another 3 kids, get 5 dogs and an abundance of cats and you would still be my kid. No matter what happens or who comes and goes, I need you to know that nothing is going to change that. You'll always be my kid. And, I'm being completely biased here obviously, but I think my baby girl is truly blessed to have you as her big brother."

The tears were back but instead of closing his chest up and making him choke they were freeing and cathartic, washing away all the unnecessary hurt from before.

"Thank you," he sniveled, nose buried in Tony's t-shirt, "I'm so sorry for just – for assuming, I don't know. I'm just –"

"Nah, I told you none of that, kid," the billionaire replied easily, turning his head to press a kiss to the top of his head before burying his nose in Peter's curls and breathing him in, feeling like coming home for the first time in weeks. "Believe it or not this is actually a normal behavior so for once you're acting like normal kids your age and I think we should celebrate with ice cream and a movie."

He snorted and jabbed, "Great parenting, _dad_, just fill up your kid with ice cream after every emotional conversation ever."

"It's called positive reinforcement, look it up, smartass," was all he got in return and then, without any prior warning, he was being picked up. With an undignified squeak he buried closer into his mentor's chest, arms and legs clinging to the man whose hands were resting lightly on his back as he was carrying him upstairs.

"So, what's it gonna be, Underoos. Stark Raving Hazelnut or Hunka-Hulka Burning Fudge," he asked once he had dropped his precious cargo on the couch in front of the TV.

Peter buried deeper into the familiar blankets, instructing F.R.I.D.A.Y. to pull up Rogue One, as his mentor went to get their ice cream ready.

Together they curled up, happy in each other's presence and when Pepper joined them later, making herself comfortable on Peter's other side and he got to feel Baby Stark kicking for the first time ever, there was nothing but joy in his heart.

_(On the back of the shirt is a picture of the Iron-Man helmet and "iron kid" written beneath it in Tony's handwriting. Peter doesn't know it yet but Baby Stark will get a similar t-shirt, with a different front but the same back. In turn, Tony will be getting the "iron dad" version of the design (in Peter's chicken scratch) for Father's Day. He has never worn anything prouder.)_


End file.
